jayluber Loc: Phoenix, AZ

Have to travel so far to find dark skies these days and only getting worse. It was suggested I get a light pollution filter for my camera.

I use Sigma 14-24 for my astro work so I cannot attach filter to end of lens. Have to use clip in filter that goes in camera between sensor and lens.

Have Canon full frame and crop (6D and 77D). Clip in filters seem expensive ($129 APS_c, and 210 for FF).

Does anyone have experience using these filters? Comments - Suggestions?

Thanks Hogs.

larryepage Loc: North Texas area

I do not have personal experience with light pollution filters, but your question came up during a PhotoPills Milky Way Photography Class earlier today. The instructor indicated that most folks are disappointed with the performance and effectiveness of these filters. I think I heard him say that they work a little better on cameras that have been modified for celestial photography (like the D810a). Perhaps someone will give you a more optimistic report than this...

jayluber Loc: Phoenix, AZ

Thank you. I don't have huge expectations for them.
There are many different filters for different wavelengths. Some are designed for modified cameras, some for non.

CaptainPhoto

I don't know how much correction you expect to get with a light pollution filter. I have one, was very costly. I used it one time doing a Milky Way photo shoot. It did not improve things that much. I recently viewed a You Tube video Milky Way Masterclass with Alyn Wallace. His response to the question about light pollution filters was "don't expect miracles". I have one for sale if you want to buy it.

manofhg Loc: Knoxville, TN

I've talked with a few regarding light pollution. The question I asked was if you have a star tracking system, why not shoot one long exposure instead of several short exposures. The answer didn't go into the deep of why, but they said that there would be less light pollution evident even though you might shoot 60 shots of 1 minute each and then compare to 1 shot of 60 minutes. Not sure why this is, but something regarding light frequencies or other deep magic that he didn't go into. He said you want to stay below about 45 secs. per shot. I know folks who shoot stars with telescopes and trackers and don't do one long exposure, but MANY short ones stacked along with a set of "dark images". I don't know whether serious astronomers use light pollution filters. I know they have filters, but for other purposes like filtering certain wavelengths and such. Using a hydrogen alpha filter would be an example, but those are specialized and have an especially high price as well. They aren't for light pollution control either.
So, no, my answer didn't help.....

larryepage Loc: North Texas area

Traditional street lights have been either sodium arc, with two very discrete yellow spectral lines that could easily be filtered out while still passing the vast majority of the spectrum intact, or mercury vapor lights, with (primarily) six very narrow, discrete colors of light...two each in the violet, orange, and green parts of the spectrum. These eight lines could be filtered out "easily," although the notch filters would, as you indicate, necessarily be pretty expensive. The big problem I see is that newer technologies of sodium lamps, with white light, and LED lights, with a quite continuous spectrum, are being used in many locations today. It would be very difficult (really impossible) to filter all of that light out and leave us anything to photograph.

Multiple exposure techniques are intended to reduce noise, not really light pollution. The idea is that noise will appear in one or maybe a few of the exposures, but not in all of them. By combining the multiple images and including only the illuminated pixels that appear in all (or at least most) of the images, only true points of light survive processing...random noise that is only in one or a few of the images is eliminated by the processing software.

I have discovered that some of what we might consider noise really isn't noise at all. Because we shoot the Milky Way in the late spring and summer, we are shooting in a situation where the ground and lower atmosphere are still warm from the previous day's heating by the sun. So a significant portion of the horizon glow is really radiation from this leftover energy. And in some cases, there can be a very slight greenish glow caused by excited oxygen molecules in the atmosphere. So after a long time and a lot of work trying to get rid of all of the atmospheric glow, I've decided to embrace it instead...still minimizing (or at least optimizing) it, but not being so put off by it.

manofhg Loc: Knoxville, TN

Thanks for that explanation. I now better understand things. Now the problem is to remember it.